Material or article handling – Apparatus for moving intersupporting articles into – within,... – Positions intersupporting article into row
Reexamination Certificate
1999-11-12
2001-10-16
Krizek, Janice L. (Department: 3652)
Material or article handling
Apparatus for moving intersupporting articles into, within,...
Positions intersupporting article into row
C271S181000, C414S790300
Reexamination Certificate
active
06302638
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to stacking stations on sortation conveying systems used to sort large orders of substantially rectangular articles, such as assorted books, packaged compact discs, packaged video cassettes, boxed software etc. More specifically, the invention relates to a mechanism that facilitates convenient removal of articles from the stacking station.
BACKGROUND OF THE INVENTION
In large distribution applications, sortation conveying systems are typically used to fulfill orders of intermingled articles such as assortments of books, video cassette containers, packaged software, compact disc containers, etc. Workers load items into the system and the articles are conveyed in single file within individual pockets on a core conveyor belt. As the assorted articles begin to move through the system on the core conveyor belt, the system reads preprinted bar code information and automatically sorts the articles into various outgoing orders. The downstream end of the sortation conveyance system normally includes a system of computer controlled diverting gates that divert articles into appropriate stacking stations for outgoing orders. Outgoing orders typically contain 100 or more articles. If an article is loaded onto the core conveyor, and it is not needed for any of the outgoing orders, it is discharged into a left over bin and returned to stock.
The assignee of the present application has developed an improved stacking station in which articles for a particular order are stacked onto an elongated and substantially horizontal accumulation tray. The articles are stacked sequentially onto the tray such that the articles are standing upright on edge, and in series side-by-side. This system is disclosed in detail in copending patent application Ser. No. 09/439,862 entitled “Discharge Stacking Station for Sortation Conveying System” by David A. Remsing, Jason M. Knas and Todd R. Eggebrecht filed on Nov. 12, 1999 incorporated herein by reference.
The disclosed discharge stacking station includes an accumulation tray that has substantial length in order to accommodate large orders of articles (e.g. preferably about 4-12 feet). The accumulation tray extends from the loading mechanism for the stacking station perpendicularly outward, and workers unload the articles for a particular order from the opposite end of the accumulation tray. Preferably, the tray has a bottom wall and a backstop wall which extends perpendicularly upward from a rear edge of the bottom wall. The bottom wall of the accumulation tray is preferably tilted downward towards the rear edge so that the force of gravity assists the alignment of articles in the accumulation tray (e.g., alignment along the bottom wall and the back wall).
As disclosed in the above referenced copending application, the stacking station preferably includes a dead plate on the accumulation tray which acts much like a bookend to stabilize the series of articles being stacked onto the accumulation tray. The dead plate is connected to a pneumatic cylinder that moves the dead plate linearly along the horizontal length of the accumulation tray. Before the first article is stacked onto the accumulation tray, the dead plate is positioned near the loading end of the accumulation tray. Then, the pneumatic cylinder is deactivated (i.e. the dead plate is connected to a dead cylinder). When the articles are being stacked onto the accumulation tray, the dead plate abuts the first stacked article to prevent tipping of the article in the accumulation tray. As additional articles are stacked onto the accumulation tray, the dead plate attached to the dead cylinder moves incrementally along the accumulation tray. It has been found that use of a dead cylinder provides the dead plate with sufficient resistance to prevent tipping of the articles in the accumulation tray during the stacking procedure, yet does not interfere with the loading of articles onto the accumulation tray. When the order is complete, the attending worker unloads the articles from the accumulation tray. After the articles have been unstacked, the dead plate is returned to the home position ready to accept the next order being stacked onto the accumulation tray. Although the system as disclosed in the above copending patent application is effective, it has been found that it would be desirable to further improve the efficiency of workers unloading articles from the accumulation tray.
SUMMARY OF THE INVENTION
The invention involves the use of an automatically controlled retractable arm that moves along the accumulation tray of the stacking station in order to: 1) ensure organized stacking of articles onto the accumulation tray; as well as 2) facilitate conveyance of articles to the end of the accumulation tray for convenient unloading. An automatically controlled actuator, such as a pneumatic cylinder, is connected to the retractable arm and positions the retractable arm between a down position in which the retractable arm is placed slightly above the accumulation tray for holding and pushing articles in the tray, and a retracted position. In its preferred form, the retractable arm is pivotally mounted for retraction. In the retracted position, the arm provides complete clearance above the accumulation tray where stacked articles are typically located. Another automatic actuator, preferably a cable-type pneumatic cylinder actuator, is used to move the retractable arm linearly along the length of the accumulation tray. The mechanism also preferably includes sensors to coordinate effective movement of the retractable arm for automatic implementation.
The mechanism operates in the following manner. Articles are stacked sequentially onto the accumulation tray in series standing upright on edge, and side-by-side. Before the first article is stacked onto the accumulation tray, the retractable arm is placed in a down position at a home location near the loading end of the accumulation tray. As the articles are stacked onto the accumulation tray, a first side of the retractable arm abuts the first stacked article much like a bookend to stabilize the series of articles being stacked onto the accumulation tray. During the stacking operation, the actuator that drives the retractable arm linearly along the length of the accumulation tray is preferably deactivated (i.e. a dead cylinder). The retractable arm is thus moved incrementally by the endmost article in the series along the accumulation tray as additional articles are stacked in series on the accumulation tray. When the order is complete, or it is otherwise desirable to unload the accumulation tray, the retractable arm automatically retracts, and is returned to the loading end of the accumulation tray slightly upstream of the last stacked article. The retractable arm is then pivoted into the down position so that a second side of the retractable arm is ready to push the series of stacked articles along the length of the accumulation tray towards the unloading end of the tray. In the down position, the retractable arm is driven linearly by the pneumatic actuator to push the series of articles toward the unloading end of the accumulation tray. When a photoelectric sensor senses the presence of articles at the unloading end of the accumulation tray, the pneumatic cylinder is momentarily deactivated. As the attending worker unloads articles from the unloading end of the accumulation tray, the photoelectric eye senses the absence of articles and the pneumatic cylinder is reactivated to again drive the retractable arm, thus supplying more articles to the unloading area of the accumulation tray. The mechanism also includes a proximity switch for the retractable arm which is located near the unloading end of the accumulation tray. When the proximity switch senses the presence of the retractable arm, the retractable arm is returned to the home position near the loading end of the accumulation tray.
It should be apparent to those skilled in the art that the mechanism provides a fully automated manner of preventing tipping of articles
Eggebrecht Todd R.
Knas Jason M.
Andrus Sceales Starke & Sawall LLP
Dorner Mfg. Corp.
Krizek Janice L.
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